Field of the Invention
The disclosure generally relates to a communication device, and more particularly, it relates to a small-size, dual-band communication device for supporting MIMO (Multi-Input and Multi-Output) functions.
Description of the Related Art
With the advancements being made in mobile communication technology, mobile devices such as portable computers, mobile phones, multimedia players, and other hybrid functional portable electronic devices have become more common. To satisfy consumer demand, mobile devices can usually perform wireless communication functions. Some devices cover a large wireless communication area; these include mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some devices cover a small wireless communication area; these include mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz.
Wireless access points are indispensable elements that allow mobile devices in a room to connect to the Internet at high speeds. However, since indoor environments have serious problems with signal reflection and multipath fading, wireless access points should process signals with different frequencies from a variety of directions simultaneously. Accordingly, it has become a critical challenge for antenna designers to design a multiband, omnidirectional antenna for use in the limited space of a wireless access point.